This invention relates generally to a dual power path drive for a rotatable threshing rotor or rotors of an agricultural combine, and more particularly, to a dual path drive such as a hydro-mechanical drive, operable for smoothly re-engaging with the rotor or rotors after disengagement therefrom, without having to wait for the rotation of the rotor or rotors to cease, and without occurrence of undesirable wear and shock to elements of the drive.
Currently, it is sought to use a dual path drive for rotatably driving rotatable elements of an agricultural combine, particularly a rotatable rotor or rotors of a threshing mechanism of the combine. Such rotors are typically relatively heavy members and are rotated at relatively high speeds, such that in the event that the drive is disengaged therefrom, for instance, as a result of being intentionally controllably disengaged by an operator, or automatically disengaged, such as when a sensor indicates that the operator has left the operator seat, it is typical practice to maintain the drive in a disengaged state to allow the rotor to rotate freely and decelerate until the rotational energy is dissipated and the rotation comes to a halt. This can take a relatively long time, depending on damping and inertia acting on the rotating elements. When the rotation has come to a halt, the drive is typically then reengaged with the rotatable element to bring them back to the desired rotating condition.
By use of a dual path drive, that is, a drive such as a hydro-mechanical drive having an input which receives power from a fluid power source such as a fluid motor and another input which receives power from a mechanical power source such as a gear box connected to an engine, or an electro-mechanical drive, which differs from a hydro-mechanical drive in that an electrical motor is used instead of a fluid motor, it is sought to provide the operating capability to re-engage the drive with the rotor as it is already rotating, such that time delays while waiting for the rotor or rotors stop rotating are reduced or substantially eliminated, without causing undesirable wear of elements and components of the drive, particularly, clutches thereof, and shock.
According to the present invention, a dual power path drive operable for rotatably driving a threshing rotor of an agricultural combine, and operable for re-engaging the drive with the rotor when already rotating, without causing undesirable time delays, wear and shock, is disclosed. The drive includes a planetary gear arrangement having an output connected to the rotor for rotation therewith, a rotatable input connected in rotatably driven relation to a rotatable output of a first power source or path which is preferably a fluid power source such as a fluid motor of a hydro-static drive conventionally controllably operable for variably rotating the output of the fluid motor, or a conventionally controllably variable speed electrical motor. The gear arrangement includes a second input, which is preferably the ring gear thereof, connectable by engagement or operation of a suitable device such as an engine-to-ring clutch, in rotatably driven relation to a rotatable output of a second power source or path connected to an engine of the combine. The device or clutch preferably includes faces or other elements connected in rotatably driven relation to the engine and to the ring gear or other input for rotation therewith, respectively, which faces or other elements can be commanded to slip one relative to the other, that is, brought into relation one to the other such that rotation of one can cause rotation of the other at some proportional speed to the one, or commanded to fully engage such that one will rotate the other at substantially the same speed. The method of the invention for engaging the drive in driving relation to the rotor while the output of the engine and the rotor are rotating, includes the steps of;
(a) commanding or operating the device or clutch to slip the faces or elements thereof or rotating the rotatable output of the first power source to bring the faces or elements to substantially matching rotational speeds; and then
(b) commanding or operating the device or clutch to fully engage.
Prior to and during steps (a) and (b) the first power source can be operated as required for bringing the elements of the planetary gear arrangement to speeds at which the device or clutch can be slipped, and for bringing the rotor speed up or down to or maintaining it at a speed within a range which allows slipping the device or clutch without undesirable effects, particularly shock and/or wear. And, if the initial rotor speed at which it is desired to re-engage the drive is within a sufficiently lower speed range, an additional engageable device or clutch such as a ring-to-frame clutch can be engaged in conjunction with the operation of the first power source for increasing the rotor speed and the speed of the elements of the gear arrangement to range wherein the first device or clutch can be slipped without the undesired effects.